Modern treaty law is codified by the Vienna Convention on the Law of Treaties, 1155 U.N.T.S. 331, T.S. No. 58 (1980), 8 I.L.M. 679 (1969). (entered in force on January 27, 1980). Although the United States is not a signatory of the Vienna Convention, U.S. courts look to the Convention for guidance on the "customary international law of treaties", see, e.g., Avero Belgium Ins. v. American Airlines, 423 F.3d 73,80 (2nd Cir. 2005).

Treaties may be bilateral (between two countries) or multilateral. Multilateral treaties and treaties to which the United States is a signatory are generally more readily available.

Research Tasks

Locate treaty text
Determine status
 • Signatories and ratification
 • Reservations and declarations
Locate implementing legislation
Locate case law and commentary
Locate administering documents
Locate legislative history / background materials

Treatises:

• Villiger, Customary International Law and Treaties: A study of their Interactions and Interrelations (JX4165 .V55 1985)
• DEVELOPMENTS OF INTERNATIONAL LAW IN TREATY MAKING (KZ1301 .D48 2005)
• INTERNATIONAL LAW DECISIONS IN NATIONAL COURTS (KF4581 .I58 1996)
• Menon, THE LAW OF TREATIES BETWEEN STATES AND INTERNATIONAL ORGANIZATIONS (JX4165 .M46 1992)
• Aust, MODERN TREATY LAW AND PRACTICE (KZ1301 .A93 2000)
• Leigh, NATIONAL TREATY LAW AND PRACTICE: AUSTRIA, CHILE, COLOMBIA, JAPAN, THE NETHERLANDS, UNITED STATES (K3342 .N383 1999)
• Gardiner, Treaty Interpretation (KZ 1304 .G37 2008)
• TREATIES AND OTHER INTERNATIONAL AGREEMENTS: THE ROLE OF THE UNITED STATES SENATE: A STUDY (Y 4.F 76/2:S.PRT.106-71)
• United Nations Treaty Handbook

Researching Treaties when the United States is a Signatory

In the United States, the treaty making process involves several steps: negotiation by the executive branch, drafting of the treaty, signature, ratification by the Senate, and upon occasion, enactment of implementing legislation.

A less formal type of international agreement, the executive agreement, bypasses the Constitutional requirement of ‘advice and consent’ by Congress. Executive agreements are frequently referred to as memoranda of understanding, or memoranda of agreement. The vast majorities of executive agreements involve matters of foreign aid, trade, and agriculture and are indirectly authorized by Congress through federal legislation. Executive agreements are binding under international law.

Treaty Text Sources

Official Sources (official sources can take years to publish new treaties):

• TREATIES AND OTHER INTERNATIONAL ACTS SERIES (T.I.A.S.) (JX235.9 .A32, HeinOnlineDepartment of State)
• UNITED STATES TREATIES (U.S.T.) (JX235.9 .A31, HeinOnline)
• UNITED STATES STATUTES AT LARGE (until 1950) (Reference KF50 .U55x, HeinOnline)

Unofficial Sources:

• CONSOLIDATED TREATIES AND INTERNATIONAL AGREEMENTS (JX235.9 .C65)
• HEIN’S UNITED STATES TREATIES AND OTHER INTERNATIONAL AGREEMENTS – Current Microfiche Service (fiche JX235.9 .A31101,HeinOnline)
• INTERNATIONAL LEGAL MATERIALS (JX 1 .I67, HeinOnline, Westlaw - ILM, LexisNexis - INTL;ILM)
• Thomas Treaties Page
• Bevans, TREATIES AND OTHER INTERNATIONAL AGREEMENTS, 1776-1949 (JX236 1968 .A5, HeinOnline)
• UNPERFECTED TREATIES OF THE UNITED STATES, 1776-1976 (JX236 1776 .U56)
• LexisNexis: INTLAW;USTRTY
• Westlaw: USTREATIES

Treaty Status Sources

• CCH CONGRESSIONAL INDEX (Reference KF49 .C6)
• A GUIDE TO THE UNITED STATES TREATIES IN FORCE (JX236.5 .G84,HeinOnline)
• Thomas 
• Treaty Actions 
• TREATIES IN FORCE (JX235.9 .A33, LexisNexis - INTL;USTIF, HeinOnline)
• United States Senate 

Treaty Interpretation and Legislative Intent

• SENATE TREATY DOCUMENTS (fiche Y 1.1/4) (formerly called Senate Executive Documents, treaty documents include the transmittal of draft treaties from the President to the Senate, analysis, and accompanying memoranda.) (Thomas)
• Congressional hearings (usually conducted by Senate Foreign Relations Committee) (Westlaw - USTESTIMONY or CONGTMY, GPO Access)
• Identify Treaty Documents and Senate hearings with CIS ANNUAL (Reference Z1223.Z7 C58x, LexisNexis - LEGIS;CISLH and CISHST) or CATALOG of UNITED STATES GOVERNMENT PUBLICATIONS (Z1223 .A18, GPO Access)
• SHEPARD’S FEDERAL STATUTE CITATIONS (Reference KF78 .S56)
• UNITED STATES CODE SERVICE (Reference KF62 1972 .L38) (full text of selected multilateral treaties and case annotations for multilateral and bilateral treaties.)

Researching Treaties when the United States is not a Signatory

Treaties that the United States is not a party to tend to be more challenging to identify and locate.

Multilateral Treaties

Multilateral treaties are generally more readily available than bilateral treaties. Most multilateral treaties whether the United States is a signatory or not, are created under the auspices of international or regional organizations, such as the World Trade Organization. Consequently, multilateral treaties can usually be found in the publications of the international organization or on their websites. Another effective method for locating multilateral treaties is to search for compilations organized by subject matter. For example, INTERNATIONAL TREATIES ON INTELLECTUAL PROPERTY (K1401 .A35 I57 1997) or AIR AND AVIATION TREATIES OF THE WORLD (JX5769 .A2 A35) or Environmental Treaties and Resource Indicators.

Treaty Indexes:

• INDEX-GUIDE TO TREATIES: BASED ON THE CONSOLIDATED TREATY SERIES (JX120 .C652)
• INDEX TO MULTILATERAL TREATIES: A CHRONOLOGICAL LIST OF MULTI-PARTY INTERNATIONAL AGREEMENTS FROM THE SIXTEENTH CENTURY THROUGH 1963, WITH CITATIONS TO THEIR TEXT (Reference JX171 .H37)
• MULTILATERAL TREATIES: INDEX AND CURRENT STATUS (Reference JX1977 .M85)
• WIKTOR, MULTILATERAL TREATY CALENDAR (1648-1995) (KZ118 .W55 1998)
• UNITED NATIONS MASTER TREATY INDEX (Reference JX170 .L422, CD-ROM in Reference Office)
• WORLD TREATY INDEX (1900-1980) (Reference JX171 .R63 1983)

Treaty Sources:

• INTERNATIONAL LEGAL MATERIALS (JX 1 .I67, HeinOnline, Westlaw - ILM, LexisNexis - INTL;ILM)
• Multilaterals Project 
• League of Nations, TREATY SERIES (1920-1946) (JX170 .L42)
• Treaties: Trade Instruments 
• UNITED NATIONS TREATY SERIES (JX170 .L421)
• Westlaw has several treaty databases and a combined database (CMB-TREATIES).

Status Sources:

• INTERNATIONAL LEGAL MATERIALS (JX 1 .I67, HeinOnline, Westlaw -ilm, LexisNexis - intl;ilm)
• MULTILATERAL TREATIES DEPOSITED WITH THE SECRETARY-GENERAL (1982-) (JX1977 .A335)
• MULTILATERAL TREATIES: INDEX AND CURRENT STATUS (Reference JX1977 .M85)

Treaty Interpretation: (Case law interpreting treaties and conventions may come from international courts or national courts. Some compilations for specific treaties are available. For example, the CISG (Convention on the International Sale of Goods) database at Pace Law School or ICSID REPORTS (Convention on the Settlement of Investment Disputes) (K3834 .A495 R46))

• INTERNATIONAL LAW REPORTS (JX68 .I56)

Bilateral Treaties

Bilateral Treaties for which the United States is not a party are the most elusive. Although some countries, such as the United Kingdom, France and Australia, compile their treaties in the comprehensive manner employed by the United States, most do not. Members of the United Nations are supposed to deposit bilateral treaties with the United Nations, but many do not.

Sources of information on bilateral treaties include national laws, official gazettes, treatises, or references in news or journal articles. When available, subject compilations such as INVESTMENT LAWS OF THE WORLD (K1112.A24 I57) and INTERNATIONAL TAX TREATIES OF ALL NATIONS (K4473.A1 I57) are an excellent option for locating bilateral treaties. The WORLD TREATY INDEX (1900-1980) (Reference JX171 .R63 1983) is helpful in identifying older bilateral treaties.

Reynolds and Flores, FOREIGN LAW: CURRENT SOURCES OF CODES AND BASIC LEGISLATION IN JURISDICTIONS OF THE WORLD (Reference K38 .R49 1989 and electronic through BEN) identifies many bilateral treaties. If all else fails, contact international or local chambers of commerce, the country desk at the U.S. Department of State, or the United States or country’s embassy or consulate.